Convictions upheld despite DNA error

The Supreme Judicial Court has decided to uphold the convictions in a first-degree murder prosecution even after finding that a prosecution witness gave mathematically erroneous DNA testimony.

“[O]ur review of the record indicates that Leanna Farnam, the chemist from the DNA unit of the State police crime laboratory who testified on behalf of the Commonwealth, made several calculation errors in her conversions of fractions into percentages, and thereby understated the likelihood that a randomly selected individual with no connection to the item could be ‘included’ as a potential contributor to the DNA samples,” Justice Margot Botsford wrote for a unanimous court.

“We conclude, however, that there was no substantial likelihood of a miscarriage of justice,” Botsford continued. “The difference of one per cent between the figures given by Farnam and the true figures was unlikely to have substantially influenced the jury’s deliberations, because the percentage of the population who were excluded as possible contributors to the DNA remained very high — over ninety-eight per cent — meaning it was still very unlikely that anyone included as a contributor had no connection to the item.”